Reducing the amount of electrical power consumed by electrical devices is becoming increasingly important, not only for cost considerations, but also due to environmental pressures. Furthermore, reducing the amount of power consumed reduces the strain on electrical infrastructure, such as electrical transmission lines and generation facilities
One way of reducing the amount of electrical power consumed by electrical devices is to reduce the voltage and current supplied to them. Most electrical devices operate normally within a supply voltage range which can be less than the nominal supply voltage. For example many devices which are designed to operate at 230 Vac work normally at voltages as low as 210 Vac. Thus reducing the supply voltage to an electrical device will often reduce the amount of power consumed. Although there may be a slight reduction in performance, such as a slight reduction in brightness of incandescent lighting and a slight reduction in the speed of a motor, in most circumstances the performance reduction is not noticeable to the user.
Various voltage control systems exist that utilise a combination of transformer-based technology and electronic switching devices such as Silicon Controlled Rectifiers (SCR), Pulse-Width Modulators (PWM) and Insulated Gate Bipolar Transistors (IGBT). However all of these technologies are expensive and create a minor interruption in the supply voltage as a result of their break-before-make technology. If the supply voltage is interrupted in this fashion, overload conditions may occur in the electrical device.
Limitations of standard E and I auto-transformers in an energy reduction scenario are a direct result of their inherent design. Auto-transformers, being fixed-ratio, non-isolating transformers, in their generic design are not capable of ensuring a fixed range of voltage output in an environment with fluctuating input voltage. Therefore, E and I auto-transformers are not ultimately suitable for widespread applications in energy reduction solutions.
Another device used for voltage control is a variac. Variacs provide a facility that is not necessary for use in energy reduction technology, being that they allow for their rated current at a wide range of voltages (typically 0 to 260V). Clearly any voltage below 205V is inappropriate for use in normal mains power, as an under voltage scenario may occur and risk damage to equipment. Variacs may be useful in laboratory testing for example, however are an impractical and prohibitively expensive solution for some other applications which require only an isolated range of voltage. In addition, variacs that are rated for use at 50 amps for example are extremely heavy and are typically oil cooled.
US patent application no 2010/0039090 discloses a voltage compensation circuit, for increasing a voltage to a load to compensate for a voltage drop in a supply voltage, and a method of bypassing the circuit. This is achieved by varying the number of windings on the transformer. However, this circuit will not be able to handle large currents when controlling the voltage to a home of factory for example. Furthermore, the circuit will not reduce a power consumption in a load.
There is therefore a need for an improved system and method for reducing power consumption in a power supply circuit.
The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge in Australia or elsewhere.